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Office of Campus Relations Press Release


Charles Schweighauser

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This Year



UIS’ fall Star Parties will focus on Mars

August 5, 2003

SPRINGFIELD – Astronomy buffs can take advantage of a once-in-a-lifetime opportunity to get a close-up look at Mars on August 27 when the red planet comes within approximately 34.6 million miles of Earth, closer than it has been at any time in the past 60,000 years, and closer than it will be again until the year 2287.

Click here to view a diagram illustrating the event described in this release. The diagram is in a pdf format.

“This is certainly the best opportunity to see Mars for at least the next 15 years,” said Charles Schweighauser, professor of Astronomy and Physics at the University of Illinois at Springfield.

Schweighauser explained that this is happening now because three separate events are occurring at nearly the same time: Mars will be at opposition – on the opposite side of the Earth from the Sun – on the night of August 28, and it will also be at perihelion, the point in its orbit when it is closest to the Sun, on August 30. These two events rarely coincide because the Earth is closer to the Sun than Mars is and our orbit is therefore smaller and faster. Mars is at opposition every 780 days, but rarely when it is also this close to its perihelion. Furthermore, the Earth will then be less than two months past its aphelion point – its farthest distance from the Sun – which brings the Earth closer to Mars’ orbit.

Schweighauser will give area residents the chance for an especially good look at this phenomenon by hosting Friday night Star Parties from 9 to 11 p.m. beginning August 29 and running every Friday night through September 26 at the UIS observatory, weather permitting.

“Mars will be bright red in the southern sky,” Schweighauser explained, “about 30 degrees above the horizon at its highest point.” That won’t be until about 1 a.m. he added, and although the observatory will not remain open that late, “that’s why this fall all the Star Parties will be an hour later than usual. It will give Mars a chance to rise higher in the sky so we have less of the Earth’s atmosphere to observe through, and thus we will have a clearer look at the planet,” he said.

Free and open to the public, Star Parties make the observatory’s three telescopes available to viewers of all ages. Reservations are not required and groups are encouraged to attend. The entrance to the observatory is located outside the southeast corner of Brookens Library on the UIS campus.

To learn if weather is suitable for viewing, call the UIS Astronomy Office at 206-6721 at 8 p.m. on the evening of the Star Party.